A fuel cell normally reforms a hydrocarbons raw fuel gas into a hydrogen-rich gas by a reformer and supplies the reformed gas to a fuel electrode of the fuel cell, and at the same time, supplies the air taken from the outside to an air electrode, and by way of an electrolyte membrane comprised of solid polymer or the like, an electrochemical reaction takes place by hydrogen gas of the fuel electrode and oxygen gas of the air electrode, to generate electric power and water.
As a fuel cell like this, for example, a fuel cell as shown in FIG. 5 has been known, where a cell D, providing with a fuel electrode B on one face of an electrolyte membrane A and an air electrode C on the other face, is sandwiched with separators H and stacked in plurality to form a stack E; end plates F are attached to both ends of the stack E; and a plurality (four pieces in the figure) of tie rods G are pieced and fastened, to unify the stack E.
The fuel electrode B (and the same applied to the air electrode C) is normally supplied with a reformed gas by way of the separator H that forms a plurality of grooves (gas passage); and, in the separator H, as shown in FIG. 6 for example, a manifold I for supplying gas is formed at one end part and communicated with each of the grooves, a gas supply port J is provided at an end part of the manifold I, a manifold K for discharging gas is formed at the other end part and communicated with each groove, and a gas exhaust outlet L is provided at an end part of the manifold K. Accordingly, the reformed gas flows from the gas supply port J into the manifold I for supplying gas, flows from the manifold I for supplying gas through each groove into the manifold K for discharging gas, and is exhausted from the manifold K for discharging gas K through the gas exhaust outlet L to the outside.
In the fuel cell composed as described above, for the sake of cell performance, it is necessary for the reformed gas to be supplied uniformly to the fuel electrode B of each cell D, but the problem was that the requirement was not satisfied. That is, in the stack E, as shown schematically in FIG. 7, the gas supply port J is connected and a tunnel-shaped inner manifold M is formed, and the reformed gas is supplied from one end part (inlet side) of the inner manifold M. In this case, since the flow velocity of the reformed gas supplied to the inner manifold M flows drops little by little, the reformed gas flows more into cells D near the inlet but the reformed gas flows less into cells D far from the inlet. Thus, dispersion occurs in electromotive force between cells D and performance of the fuel cell drops.
To solve a problem like this, conventionally for example, a fuel cell is known, which provides a space for diffusing gas and a gas flow regulating plate at a gas intake part of a manifold on the inlet side to supply a reformed gas to each cell (Japanese Patent Laid-Open No.Hei.8-293318). Also, a fuel cell is disclosed, which forms a fuel gas channel to become shallower gently from the inlet side to the outlet side and provides a flow regulating plate in the fuel gas channel (Japanese Patent Laid-Open No. Hei.7-288133). Besides the fuel, distribution of an oxidant, the effect of which on a cathode (air electrode) reaction is big, is also a problem. Further, distribution of cooling water, which leads to a non-uniform temperature distribution, is also a problem.
However, these improved fuel cells involves shortcomings of making the construction complicate and increasing structural parts. Thus, the present invention aims to provide a fuel cell that can distribute and supply the reformed gas to each cell, without making the construction complicated, while minimizing the increase in parts count.